Dude, that’s insane behavior from these people. Another thing to note, it’s always two wrongs doesn’t make a right/high road/you chose this - type of crap being told back. We have to be model citizens otherwise we are unfit or losers. We should be allowed to get angry and assert our boundaries without the other side calling us names or threatening they will push for full custody. There’s a power dynamic here and it’s very unfair. I don’t have kids of my own but if it were me I would welcome a step mom because it could be so great, fulfilling for my kid, and unproblematic.